The effect of imipramine on Mg2+ efflux in NaCl medium (Na+/Mg2+ antiport), on Mg2+ efflux in choline.Cl medium (choline/Mg2+ antiport) and on Mg2+ efflux in sucrose medium (Cl- -coupled Mg2+ efflux) was investigated in rat erythrocytes. In non-Mg2+-loaded rat erythrocytes, imipramine stimulated Na+/Mg2+ antiport but inhibited choline/Mg2+ antiport and Cl- -coupled Mg2+ efflux. The same effect ...

Magnesium ions (Mg2+) are divalent cations essential for various cellular functions. Mg2+ homeostasis is maintained through Mg2+ channels such as MgtE, a prokaryotic Mg2+ channel whose gating is regulated by intracellular Mg2+ levels. Our previous crystal structure of MgtE in the Mg2+-bound, closed state revealed the existence of seven crystallographically-independent Mg2+-binding sites, Mg1-Mg...

The effects of temperature (0, 5, 10, 15 and 20 °C) and of anoxia (at 5 °C) on extracellular Mg2+ concentration ([Mg2+]e), intracellular pH (pHi) and ATP and lactate levels were investigated in intermoult adults of the common shrimp Crangon crangon. All animals caught in summer (summer animals) showed a slight but significant increase in [Mg2+]e at low temperatures. In contrast, at ever...

Extracellular magnesium ions [Mg2+]o are known to regulate functions of endothelial cells, but whether [Mg2+]o can alter intracellular free ionized magnesium [Mg2+]i in these cells remains unknown. The present studies, using digital imaging microscopy and the Mg2+ fluorescent probe, mag-fura-2, determined effects of elevation of [Mg2+]o on [Mg2+]i in cultured human aortic endothelial cells. Wit...

The Mg2+ fluorescent dye mag-fura 2, entrapped in cells or organelles, has frequently been used for dual excitation ratio-metric determinations of free ionic Mg2+ concentrations in eukaryotic, mostly mammalian cells. Here we report its successful application to measure free Mg2+ concentrations ([Mg2+]i) in Salmonella enterica cells. When kept in nominally Mg2+ free buffer (resting conditions), ...

The concentration of intracellular free Mg2+ ([Mg2+]i) in erythrocytes, measured by means of 31P NMR and using a dissociation constant for MgATP of 38-50 microM, amounted to 0.2 mM [Mg2+]i in the erythrocytes of various species, was not significantly different and was independent of their total Mg2+ content. The more probable value of [Mg2+]i using the more realistic KD of Mg ATP or the null-po...

Lung contains both Mg2+-dependent and Mg2+-independent phosphatidate phosphohydrolase activities. Addition of Triton X-100 (0.5%) or chlorpromazine (1 mM) leads to a marked increase in the total phosphatidate phosphohydrolase activity in rat lung microsomes (microsomal fractions), but a decrease in the Mg2+-dependent activity. These observations suggest that the Mg2+-independent activity is sti...

This study examines the routes by which Mg2+ leaves cultured ovine ruminal epithelial cells (REC). Mg2+-loaded (6 mM) REC were incubated in completely Mg2+-free solutions with varying Na+ concentrations, and the Mg2+ extrusion rate was calculated from the increase of the Mg2+ concentration in the incubation medium determined with the aid of the fluorescent probe mag-fura 2 (Na+ salt). In other ...